kyle called himself the most lethal in u.s. history and was outspoken for gun advocacy. >> every shot i took, i felt extremely testified. >> >> reporter: police arrested a former marine who is believed to have left the service in 2010. the sheriff said three men parentally went to the gun range together. after the shooting. he retreated to his sister's house and told her about the incident. she called police and after a short pursuit. he was arrested. chris kyle and chad littlefield were involved in helping veterans with pts different, however, it was uncertain if he were the counselor veteran they were counseling. >> at this point, he hasn't made any comment to law enforcement as to why he did it. >> reporter: travis cox knew both kyle and littlefield and remembered them as men with a vision to help veterans >> i think chris would want to be known as a great family man. more than anything, a good husband and a good father, a good seal. a great american. >> reporter: kyle leaves behind a wife and two children. ktvu channel "2 n